With all the buzz surrounding the X-37B, it's a wonder it's being called 'top secret' anymore. The U.S. Air Force is set to launch the X-37B for the third time on Dec. 11 on a classified mission that has everyone speculating: what exactly does the United States intend to use the X-37B for?

Developed by Boeing, the X-37B (also known as the Orbital Test Vehicle, or OTV) is officially referred to as a showcase of reusable space technologies. It originated from a Boeing-NASA program back in 1999, then was shifted to DARPA, and finally to the U.S. Air Force.

"The X-37B Orbital Test Vehicle is an unmanned space vehicle that will be used by the United States Air Force to explore reusable vehicle technologies in support of long-term space objectives. These objectives include space experimentation, risk reduction, and concept of operations development. Boeing's involvement in the program began in 1999," says Boeing.

The Air Force's Rapid Capabilities Office, which runs the X-37B program, also states that the OTV missions are to test out a reusable unmanned space test platform for the Air Force.

Many people, however, have questioned the motives of such a vehicle.

Some believe that the X-37B is essentially a high-altitude bomber, capable of delivering precision strikes from the safety and speed of low orbit around the Earth. Others believe it could be used as a U.S. strike force against satellites. Some security experts even think it's simply a decoy to distract Chinese and foreign intelligence agencies.

The X-37B being launched on Dec. 11 has already undergone two previous missions. OTV-1 lasted 224 days in space, and the second one spent 469 days in orbit, completing its mission on June 16 2012. Many thought the second mission was merely a cover for the United States to spy on the Chinese.

The third mission was delayed due to a flaw in the rocket systems, but after hunting down the bug, all systems are ready to be fired up on Tuesday.

What exactly the Air Force really intends to use the X-37B may never be known, but one thing's for certain - everyone's going to be wondering.